CAN - Controller Area Network
contents
The Controller Area Network (CAN) bus is a high-integrity serial communication protocol designed for real-time data exchange in embedded systems, particularly in automotive and industrial applications. It operates on a multi-master, message-oriented architecture, allowing multiple devices (nodes) to communicate on the same network without a central controller.
Interact#
pip install python-can
pip install python-can-utils
import can
bus = can.Bus()
while True:
msg = can.Message(3, data=[0 for _ in range(8)])
bus.send(msg)
- Tbruno25/can-explorer - Visualize CAN Bus messages in real time
UDS#
Unified Diagnostic Services (UDS) is a communication protocol used in automotive Electronic Control Units (ECUs) to enable diagnostics, firmware updates, routine testing and more.
Implementation#
- pylessard/python-udsoncan - Python implementation of UDS (ISO-14229) standard.
- driftregion/iso14229 - C implementation of ISO 14229 (UDS) server and client for embedded systems
SID#
| UDS SID (Request) | UDS SID (Response) | UDS Service | Details |
|---|---|---|---|
| 0x10 | 0x50 | Diagnostic session control | Control which UDS services are available. |
| 0x11 | 0x51 | ECU Reset | It resets the ECU (includes hard reset, key off and soft reset) |
| 0x27 | 0x67 | Security access | It enables use of security critical services via authentication. |
| 0x28 | 0x68 | Communication control | This field turns send/receive of messages ON or OFF in the ECU. |
| 0x29 | 0x69 | Aunthentication | Enables more advanced authentication vs. 0x27 (PKI based exchange). |
| 0x3E | 0x7E | Tester present | Send a heartbeat message periodically to remain in existing session . |
| 0x83 | 0xC3 | Access timing parameters | View/Modify timing parameters used in client/server communication. |
| 0x84 | 0xC4 | Secured Data Transmission | Send encrypted data via ISO 15764 (extended data link security) |
| 0x85 | 0xC5 | Control DTC Settings | Enable/Disable detection of errors (e.g. used during diagnostics) |
| 0x86 | 0xC6 | Response On Event | Request that ECU processes a service request if an event happens |
| 0x87 | 0xC7 | Link Control | Set the baud rate for diagnostic access |
| 0x22 | 0x62 | Read Data by Identifier | Read data from targetted ECU - e.g. VIN, sensor data etc. |
| 0x23 | 0x63 | Read Data by Address | Read data from physical memory (e.g. to understand software behaviour) |
| 0x24 | 0x64 | Read Scaling Data By Identifier | Read information about how to scale data identifiers |
| 0x2A | 0x6A | Read Data by Identifier Periodic | Request ECU to broadcast sensor data at slow/medium/fast/stop rate |
| 0x2C | 0x6C | Dynamically Define Data Identifier | Define data parameter for use in 0x22 or 0x2A dynamically |
| 0x2E | 0x6E | Write Data By Identifier | Program specific variables determined by data parameters |
| 0x3D | 0x7D | Write Memory By address | Write information to the ECU’s memory |
| 0x14 | 0x54 | Clear Diagnostic Information | Delete stored DTCs |
| 0x19 | 0x59 | Read DTC Information | Read stored DTCs as well as related information |
| 0x2F | 0x6F | Input Output Control By Identifier | Gain control over ECU analog/digital inputs/outputs |
| 0x31 | 0x71 | Routine Control | Initiate/stop routines (e.g. self testing, erasing of flash memory) |
| 0x34 | 0x74 | Request Download | Start request to add software/data to ECU (including location/size) |
| 0x35 | 0x75 | Request Upload | Start request to read software/data from ECU (including location/size) |
| 0x36 | 0x76 | Transfer Data | Perform actual transfer of data following use of 0x74/0x75 |
| 0x37 | 0x77 | Request Transfer Exit | Stop the transfer of data |
| 0x38 | 0x78 | Request File Transfer | Perform a file download/upload to/from the ECU |
| 0x7F | Negative Response | Send with a negative response code when a request can not be handled. |